NORTH CHARLESTON, South Carolina (Reuters) - Labor union officials say they could postpone a vote seeking to organize 3,000 workers at Boeing Co's factory here in South Carolina if their campaign fails to gain enough traction against fierce opposition from the company and local politicians.

Organizers for the International Association of Machinists (IAM) are going door-to-door this week to gauge backing for the April 22 vote, and to make their case that union representation in the North Charleston plant would mean better pay and less taxing work schedules.